Asynchronous motor with external rotor - has series of ventilation openings for more intensive cooling of internal stator

摘要

Small inverted induction motors of the enclosed ventilated type, have the cooling of the internal stator (100) improved by causing positive air flow past at least part of the windings. Such cooling allows a greater power output from the same frame size with the same temperature rise. The motor may be provided with end guards having air inlet and outlet spaces (108, 109) and fan blades (110) on an extension of one rotor end ring (111). Air flowing into the machine (106) passes through spokes in the rotor hub and enters the space (104) surrounding the windings (102), flows past these to the opposite end of the machine (105) and exhausts (109). The necessry differential pressure is provided by the vanes on the end rings or by an external fan on the rotor.